Steam jet crimping method and apparatus

ABSTRACT

Improved steam jet crimping using a rearward exhaust of steam is achieved by use of a vacuum conduit with a screen having myriad small apertures and an effective open area of at least 35 percent, preferably 45 percent at the steam-yarn separation area. The apertures should have a diameter less than 0.01 inch.

United States Patent [191 [111 3,763,525 Washington Oct. 9, 1973 STEAM JET CRIMPING METHOD AND [56] References Cited APPARATUS UNITED STATES PATENTS [75] Inventor: James MacKnight Washington, 3,409,956 11/1968 Longbottom et a]. 28/ 1.3 Chester, Va, 3,440,701 4/1969 Irwin et al 28/72.ll [73] Assrgnee: llnld IYh;m|cal Corporation, New Primary Examiner Louis K. Rimrodt or Attorney-Richard A. Anderson et al. [22] Filed: Dec. 1, 1971 21 Appl. No.: 203,616 [571 ABSTRACT Improved steam jet crimping using a rearward exhaust of steam is achieved by use of a vacuum conduit with [52] U.S. Cl 28/l.3, 28/].4, 2288/7722Jll2, a Screen having myriad Small apertures and an effec tive open area of at least 35 percent, preferably 45 2; g g ?2 percent at the steam-yarn separation area. The aper- 1 0 tures should have a diameter less than 0.01 inch.

11 Claims, 2 Drawing Figures VACUUM SOURCE PATENTEU UB7 9 I 75 INVENTOR.

James M. Washington 124/4 M4 AT TOR/V5 Y STEAM JET CRIMPING METHOD AND APPARATUS BACKGROUND OF THE INVENTION This invention relates to apparatus and process for texturing yarn, more specifically, improved rearwardly exhausting steam jet crimping process and apparatus.

This invention is an improvement of the apparatus and process disclosed in U. S. Pat. No. 3,409,956 to Longbottom and Huggins, pertinent portions of which are hereby incorporated by reference. High speed operation, above 3,000 feet per minute, of the prior art rearward-exhaust steam jet for crimping often resulted in jet inoperability because of problems labeled blow out and burn out. Blow out is characterized by formation of an extremely unstable plug of crimped yarn in the stuffing tube, so the plug of crimped yarn eventually blows out of the stuffing tube and crimping no longer occurs. Bum out manifests itself in the form of melted yarn which partially or totally blocks the jet. High speed moving pictures of the prior art rearward-exhaustin g steam jet in operation showing the zone of plug formation have shown filaments of yarn being blown back through the rear exhaust vents in the steam exitplate where the yarn impinges on the plug of yarn and the steam exhausts rearwardly. Filament blow back is a potential cause for both blow out and burn out.

SUMMARY OF THE INVENTION The prior art rearward-exhausting jet described in the Longbottom and Huggins patent was improved by replacing the fluid'exit plate with a screen having a myriad of small apertures and having an effective open area of at least 35 percent and by improving the steam exhaust flow by adding a conduit under vacuum to assist flow of the exhaust steam. The apertures in the screen shoulder preferably have a diameter of less than 0.01 inch, and the screen should have an effective area of at least 35 percent, preferably at least 45 percent. The preferred screen used in this invention is a collimated hole structure available from Brunswick. This screen is uniquely suited for the separation of steam from yarn, having about 5,000 small apertures of 0.005 inch diameter and an effective 50 percent open area. However, as with the prior art apparatus, any heated fluid may be used to crimp the yarn. When steam is used, the steam temperature should be between about 220 and 350C. but preferably below about 300C. The steam pressure should be between about 50 and 110 psig, preferably between about 75 and about 95 psig. The vacuum on the steam exhaust conduit should be between about 560 and 750 mm of Hg.

I v BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows across section along the length of the preferred rearwardly-exhausting steam jet crimping apparatus.

FIG. 2 is a cross section of the jet taken along line 2--2 in FIG. 1 and shows the screenstructure of collimated holes.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing in the figure, heated fluid such as steam enters through fluid inlet 1 (or steam nozzle). This steam nozzle or fluid inlet 1 is held in position by set screw 2 in nozzle housing 3. Nozzle housing 3 is an integral piece also containing transverse passage 4 for yarn entrance and passage 9 (or energy tube) which imparts heat and energy to the yarn so that it may be compacted against a plug of previously crimped yarn in texturizing chamber 7 also called a stuffer tube. Pre-heat tube 10 is an extension and continuation of energy tube 9. Steam line,not shown, is connected to male connector 8. Steam entering through steam nozzle 1 picks up yarn at transverse passage 4 and imparts heat and energy in passage 9 which also imparts heat in preheat tube 10 and impacts the yarn against the plug of previously crimped yarn in stuffer tube or texturizing chamber 7. Steam then exhausts through a screen 6 such as a collimated hole structure and exhausts rearwardly into the annular chamber around the pre-heat tube 10 formed by exhaust housing 5 which can be a female branch tee. The vacuum conduit connects to female branch tee or exhaust housing 5.

EXAMPLE 1 Example I gives a head-to-head comparison of the prior art rearward-exhausting steam jet crimper with the improved steam jet crimper having a collimated hole structure rather than the fluid exit plate and using vacuum to assist the exhaust of steam as it exhausts rearwardly across the pre-heat tube. Both jet crimpers operated at a speed of 5,000 feet per minute with yarn having a draw ratio of 3.11 imparted in a two-stage draw, the first draw roll having a temperature of 50 and the second draw roll temperature of 180. The temperature on the heat set rolls during crimp pull-out was 165C. The steam exhaust was assisted with a conduit under 740 mm Hg absolute pressure, in the test labeled This invention. Following are the conditions and results using 1,125 denier yarn with the two jets.

TABLE I This Invention Prior Art Jet Temperature, C. 254 260 Jet Pressure, psig 96 CEAB 29.9 15.4 CPI [2.1 9.6

As can be seen in the table, the temperature of the steam in the jet is around 260 in both the prior art and the jet of this invention. Also, the steam pressure at the jet is very similar. CEAB stands for crimp elongation after boil and is expressed as the difference in length over the original length expressed as a percent. This test is an effective measure of the degree of crimp attained in the jet. The CEAB test is as follows: The length of yarn is boiled for 30 minutes in water, then placed in an oven at C. for 10 minutes and removed and allowed to stabilize for 2 hours at 70F. at 65 percent relative humidity. Then the original length is determined by hanging the yarn with a weight equal to 0.002 gram'per denier and marking it. Then a weight equal to 0.5 gram per denier is hung on the same yarn, and exactly 30 seconds later the length to which the yarn has stretched is noted. Crimps per inch CPI are measured by counting and recording every turning point of the filament along a given length, two turning points equaling l crimp.

EXAMPLE [1 Example II is another comparison of the jet of this invention with the prior art jet, but using 2,250 denier yarn. Conditions and results were as follows:

TABLE 11 Jet from This Prior Art lnvention Yarn speed entering jet, fpm. 4500 5000 Yarn temperature entering jet, C. 160 160 Yarn draw ratio 3.11 3.11 Steam temperature at nozzle, C. 300 282 Steam pressure at nozzle, psig. 98 102 Denier (Drawn, untextured) 2250 2250 CEAB 16.8 24.4

DISCUSSION It can be seen from Example 1 that by means of the apparatus and process of this invention, the amount of crimping is surprisingly increased from 15.4 to 29.9 percent (nearly double) CEAB using steam that has 6 pounds less pressure and is 9 cooler, as compared to the prior art test. Also, the number of crimps increased from 9.6 to 12.1 crimps per inch. Thus, the improved apparatus and method give surprisingly significantly improved texturing results in addition to preventing filament blow back. Similar significantly improved surprising results can be seen from the data in Example 11.

1 claim:

1. 1n a process for texturizing yarn which comprises contacting yarn with a current of heated fluid in a preheat zone to heat the yarn, directing the heated yarn under the action of the fluid against a yarn plug contained in a texturizing zone, said texturizing zone having a larger cross-sectional area than the crosssectional area of said pre-heat zone and disposed with relation to said pre-heat zone such as to form an annulus between the inner periphery of said texturizing zone and the outer periphery of said pre-heat zone, maintaining said texturizing zone under reduced pressure with respect to the pressure in said pre-heat zone, continuously exhausting said fluid through a plurality of passageways in said annulus in a direction substantially opposite to the direction of yarn travel through said texturizing zone, causing the heated fluid to escape from the texturizing zone through said passageways whereby a major portion of the pre-heat zone is surrounded with said exhausted fluid, and continuously discharging said texturized yarn from said texturizing zone at a lower linear rate than the feed rate of said yarn to said texturizing zone, the improvement comprising exhausting said fluid through a screen having myriad small apertures and having an effective open area of at least 35%, and assisting exhaust of said fluid by means of a conduit under vacuum.

2. Process of claim 1 wherein said apertures have a diameter less than 0.01 inch.

3. Process of claim 2 wherein said screen has an effective area of at least 45 percent.

4. Process of claim 3 wherein said screen is a collimated holes structure.

5. Process of claim 2 wherein the fluid is steam, the steam temperature is between about 220 and about 350C., the steam pressure is between about 50 and 1 10 psig., and the vacuum at steam exhaust is between about 560 and 750 mm Hg. v

6. Process of claim 5 wherein the steam temperature is below about 300C. and steam pressure is between about and about psig.

7. In an apparatus for texturizing yarn which comprises an injector having an internally disposed passage for yarn, fluid inlet means for supplying a heated fluid under pressure through said injector passage a texturizing chamber concentrically disposed at one end of said injector passage and being adapted to contain a compacted yarn mass, said texturizing chamber having a larger cross-sectional area than the cross-sectional area of said injector such as to form an annulus between the outer periphery of said injector and the inner periphery of said texturizing chamber and fluid exit means positioned at said annulus adapted to discharge fluid from said texturizing zone in a direction substantially opposite to yarn path travel, the improvement comprising a screen positioned in said fluid exit means, said screen having myriad small apertures and an effective open area of at least 35%, and means to exhaust said fluid under vacuum.

8. Apparatus of claim 7 wherein said apertures have a diameter less than 0.01 inch.

9. Apparatus of claim 8 wherein said screen has an effective area of at least 45 percent.

10. Apparatus of claim 9 wherein said screen is a collimated holes structure.

11. Apparatus of claim 7 wherein said fluid inlet means has an internal diameter of from about 0.045 to about 0.080 inch, said injector passage for yarn has an internal diameter of from about 0.080 to about 0.140 inch, and a length of from about 3.5 to about 5.5 inches, and said texturizing chamber has a diameter from about 0.400 to about 0.625 inch and a length of from about 4.0 to about 9.0 inches. 

1. In a process for texturizing yarn which comprises contacting yarn with a current of heated fluid in a pre-heat zone to heat the yarn, directing the heated yarn under the action of the fluid against a yarn plug contained in a texturizing zone, said texturizing zone having a larger cross-sectional area than the cross-sectional area of said pre-heat zone and disposed with relation to said pre-heat zone such as to form an annulus between the inner periphery of said texturizing zone and the outer periphery of said pre-heat zone, maintaining said texturizing zone under reduced pressure with respect to the pressure in said pre-heat zone, continuously exhausting said fluid through a plurality of passageways in said annulus in a direction substantially opposite to the direction of yarn travel through said texturizing zone, causing the heated fluid to escape from the texturizing zone through said passageways whereby a major portion of the pre-heat zone is surrounded with said exhausted fluid, and continuously discharging said texturized yarn from said texturizing zone at a lower linear rate than the feed rate of said yarn to said texturizing zone, the improvement comprising exhausting said fluid through a screen having myriad small apertures and having an effective open area of at least 35%, and assisting exhaust of said fluid by means of a conduit under vacuum.
 2. Process of claim 1 wherein said apertures have a diameter less than 0.01 inch.
 3. Process of claim 2 wherein said screen has an effective area of at least 45 percent.
 4. Process of claim 3 wherein said screen is a collimated holes structure.
 5. Process of claim 2 wherein the fluid is steam, the steam temperature is between about 220* and about 350*C., the steam pressure is between about 50 and 110 psig., and the vacuum at steam exhaust is between about 560 and 750 mm Hg.
 6. Process of claim 5 wherein the steam temperature is below about 300*C. and steam pressure is between about 75 and about 95 psig.
 7. In an apparatus for texturizing yarn which comprises an injector having an internally disposed passage for yarn, fluid inlet means for supplying a heated fluid under pressure through said injector passage a texturizing chamber concentrically disposed at one end of said injector passage and being adapted to contain a compacted yarn mass, said texturizing chamber having a larger cross-sectional area than the cross-sectional area of said injector such as to form an annulus between the outer periphery of said injector and the inner periphery of said texturizing chamber and fluid exit means positioned at said annulus adapted to discharge fluid from said texturizing zone in a direction substantially opposite to yarn path travel, the improvement comprising a screen positioned in said fluid exit means, said screen having myriad small apertures and an effective open area of at least 35%, and means to exhaust said fluid under vacuum.
 8. Apparatus of claim 7 wherein said apertures have a diameter less than 0.01 inch.
 9. Apparatus of claim 8 wherein said screen has an effective area of at least 45 percent.
 10. Apparatus of claim 9 wherein said screen is a collimated holes structure.
 11. Apparatus of claim 7 wherein said fluid inlet means has an internal diameter of from about 0.045 TO about 0.080 inch, said injector passage for yarn has an internal diameter of from about 0.080 to about 0.140 inch, and a length of from about 3.5 to about 5.5 inches, and said texturizing chamber has a diameter from about 0.400 to about 0.625 inch and a length of from about 4.0 to about 9.0 inches. 